I'm a newbie video contributor myself, and just like you I started out as a vector contributor. I now have a portfolio of 50 videos, but I've had a handful of sales across sites.
Sales are indeed a little scarce compared to vector images, something I already expected; after all, the video market is not as huge as the vector/photo market and also more expensive for buyers. Perhaps animations are sold even less than actual footage.
Looking at your portfolio I'd say the quality is there. If I were you I'd try to diversify your portfolio. You have a lot of looping background animations, but that genre is oversaturated.